package com.zhuss.util;
import java.security.AlgorithmParameters;
import java.security.Key;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

public class AES {
  // 算法名
  public static final String KEY_NAME = "AES";
  // 加解密算法/模式/填充方式
  // ECB模式只用密钥即可对数据进行加密解密，CBC模式需要添加一个iv
  public static final String CIPHER_ALGORITHM = "AES/CBC/PKCS7Padding";

  /**
   * 微信 数据解密<br/>
   * 对称解密使用的算法为 AES-128-CBC，数据采用PKCS#7填充<br/>
   * 对称解密的目标密文:encrypted=Base64_Decode(encryptData)<br/>
   * 对称解密秘钥:key = Base64_Decode(session_key),aeskey是16字节<br/>
   * 对称解密算法初始向量:iv = Base64_Decode(iv),同样是16字节<br/>
   *
   * @param encrypted 目标密文
   * @param session_key 会话ID
   * @param iv 加密算法的初始向量
   */
  public static String wxDecrypt(String encrypted, String session_key, String iv) {
    String json = null;
    byte[] encrypted64 = Base64.decodeBase64(encrypted);
    byte[] key64 = Base64.decodeBase64(session_key);
    byte[] iv64 = Base64.decodeBase64(iv);
    try {
      init();
      json = new String(decrypt(encrypted64, key64, generateIV(iv64)));
    } catch (Exception e) {
      e.printStackTrace();
    }
    return json;
  }

  /**
   * 初始化密钥
   */
  public static void init() throws Exception {
    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    KeyGenerator.getInstance(KEY_NAME).init(128);
  }

  /**
   * 生成iv
   */
  public static AlgorithmParameters generateIV(byte[] iv) throws Exception {
    // iv 为一个 16 字节的数组，这里采用和 iOS 端一样的构造方法，数据全为0
    // Arrays.fill(iv, (byte) 0x00);
    AlgorithmParameters params = AlgorithmParameters.getInstance(KEY_NAME);
    params.init(new IvParameterSpec(iv));
    return params;
  }

  /**
   * 生成解密
   */
  public static byte[] decrypt(byte[] encryptedData, byte[] keyBytes, AlgorithmParameters iv)
      throws Exception {
    Key key = new SecretKeySpec(keyBytes, KEY_NAME);
    Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
    // 设置为解密模式
    cipher.init(Cipher.DECRYPT_MODE, key, iv);
    return cipher.doFinal(encryptedData);
  }
  
  public static String decodeUserInfo(String encrypted, String sessionKey, String iv) {
	  String json = wxDecrypt(encrypted, sessionKey, iv);
	  System.out.println(json);
	  return json;
  }
  
  public static void main(String[] args) {
	  String encrypted = "RYHHquwz+jmFZqYk1K5I5WjjRHCI7qYtxBEYgnLrylTiIBd55H8Ff8v3GYpkNX4ZwGFXfTCTCgRKuYJK5xWpiN/aGnC5II6HGbMh2YiNhtqZcVC8w3XxZNY8sdAKxlY6tsPu69NmKzu5ljVIanMPzr7hqUV6Ne1kpTYuWYWKCurBuUd0KSmm3hZqg7eKARy+mx8YSd7Ud0Cunhk/gHu5ew==";
	  String sessionKey = "ns5ied48YKD54NYTGRYBsg==";
	  String iv = "3uco1oSpZ6Mx1eEnwC+f7A==";
	  decodeUserInfo(encrypted, sessionKey, iv);
}


}

